Rheasilvia is the tallest mountain in our Solar System

Rheasilvia is the most prominent surface feature on the asteroid Vesta, it is the tallest mountain in the Solar System and is thought to be an impact crater. It is 505 km (314 mi) in diameter, which is 90% the diameter of Vesta’s 529 km(329 mi).

The enormous asteroid Vesta was assumed more like a small, rocky planet than other space rocks wandering around the asteroid belt between Mars and Jupiter, according to UCLA’s Christopher Russell, principal investigator of the Dawn spacecraft. Beleived to have crust, mantle and core like Earth.

NASA’s Dawn mission revealed the presence of two large, relatively shallow impact craters in the south polar region, one with a high-standing central peak. The shallowness and prominent central peak are reminiscent of large craters on some icy satellites that may have experienced strong topographic relaxation. The location of these basins near the south pole is also unusual and suggests true polar wander, which requires relaxation of the rotational bulge. Thus, we use the finite element method and a viscoelastic rheology to examine the feasibility of relaxation processes operating on Vesta. Given the plausible thermal state of Vesta by the decay of long-lived radioactive elements, we find that the lithosphere is not compliant enough to allow strong relaxation of the large south polar craters, and thus the peculiar morphology is possibly a product of the formation of these large basins at a planetary scale. Additionally, the asteroid has not been warm enough to permit the relaxation of the rotational bulge. Consequently, these craters both happened to form near the south pole, as unlikely as that is.

The second tallest mountain of our solar system is from Mars- Olympus Mons .

It is the youngest of the large volcanoes on Mars, having formed during Mars’s Hesperian Period ( a time period on mars characterized for widespread volcanic activity ~3900 Million Years ago). It is currently the largest volcano discovered in the Solar System and had been known to astronomers since the late 19th century.The extraordinary size of Olympus Mons is likely because Mars lacks mobile tectonic plates. Unlike on Earth, the crust of Mars remains fixed over a stationary hotspot, and a volcano can continue to discharge lava until it reaches an enormous height.

Olympus Mons shows that there is a composition of 44% silicates, 17.5% iron oxides, giving the planet its red coloration, 7% aluminum, 6% magnesium, 6% calcium, and particularly high proportions of sulfur oxide with 7%. These results point to the fact that the surface is largely composed of basalts and other mafic rocks, which would have erupted as low viscosity lava flows and hence lead to the low gradients on the surface of the planet.

Acknowledgements

The author is thankful to “Rheasilvia” and “Olympus Mons”Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program for making the article available for readers and encouraging to develop genuine interests in planetary science.